Types of blood include blood group A, B, AB and O, as MedicineNet details. Each person has one of these blood types, and each person has either Rh-positive or Rh-negative blood.
Different types of blood are classified based on the presence of certain markers or antigens, which are substances that stimulate an immune response in the body, found in the plasma or the red blood cells. If a person has blood group B, it means that the person has antibodies against blood group A. People with blood group AB do not have antibodies against blood groups A and B, and they are knowns as universal recipients because they can receive blood from all the groups. People whose blood type is O have both anti-A and anti-B antibodies, and they are universal donors because they can give blood to any person regardless of blood type, as explained by WebMD.
People whose blood is Rh-positive have a specific red blood cell antigen in the blood, and they can receive Rh-negative blood, which is the blood that lacks this antigen, according to Mayo Clinic and MedicineNet. However, people with Rh-negative blood can only receive Rh-negative blood, and mismatching blood types during blood transfusions results in immune-related reactions in which the immune system responds against the new blood, as WebMD describes.